This invention concerns automatic weapons and more particularly is concerned with improvements in gas operated automatic weapons.
Infantry squad, platoon and company level operations often require the fire power of fully automatic weapons with rates of fire as is presently afforded by the belt-fed, tripod-mounted machine guns. The fully automatic capability of the basic shoulder weapon of many modern armies does not satisfactorily fulfill this requirement since these weapons are generally magazine fed and hence cannot provide this level of fire power on a sustained basis.
In addition, these weapons generally are not effective in the fully automatic mode of fire since the rates of fire and the design of these particular weapons is such that it is impossible to effectively direct the fire after the initial few rounds.
The belt-fed, tripod-mounted machine gun, while suitable for defensive situations, is ill-adapted to assault or offensive operations due to its weight and bulk, even when refitted for shoulder fire. Furthermore, the use of such weapon is complicated from a military logistics standpoint since these weapons are only issued on an organizational unit basis, i.e., each company or platoon is issued a predetermined number of such weapons and a limited number of trained gunners are assigned to each unit. This creates a logistics problem since the need for such automatic weapon fire power varies with the given tactical situation.
It would thus be advantageous if such automatic weapons capability could be afforded to each infantry unit on a more flexible basis and such logistics problems could be eliminated.
Such capability could be provided by a shoulderfired, belt-fed semi-automatic weapon which was light in weight and could be fired with sufficient accuracy such that such weapons could be issued to each infantryman at the squad level as the basic weapon, with a ready conversion to automatic firing providing a tremendous enhancement of the fire power of the infantry unit.
Such a firearm would necessarily be required to meet certain additional essential or highly desirable design criteria for military weaponry. For example, such weapons must be very reliable and readily field stripped in order to correct any malfunctioning which may occur without the use of tools. An example of a highly desirable feature is a capability for right or left handed firing of the weapon in many military operations, particularly in operations conducted through urban areas. That is, the feeding of belt-carried ammunition should be able to be done from either side since the tactics of the situation often involve firing from concealed positions against a building wall on either side of the street.
In U.S. Pat. Nos. 3,776,096 and 3,853,035, both issued to the present inventor, is disclosed such a shoulder-fired automatic weapon which is gas operated as are many such automatic weapons. However, in the design disclosed therein, the gas porting is located just ahead of the barrel chamber such that relatively high pressure gas is utilized to operate the various mechanism to obtain advantages over those conventional designs which are operated by gas pressure ported at the forward point along the weapon barrel. The major drawback of the conventional designs is that they necessitate long operating rods extending forwardly to the gas port, increasing the bulk and weight of the weapon and adversely affecting its balance characteristics.
This specific advantage of the design disclosed in those patents is afforded without the necessity for the use of gas pressure accumulator devices to reduce excessive forces which would otherwise be created. This is done by a unique concept, in which the sequencing of operation is not carried out directly by the movement of an operating rod, but rather there is provided a sequential operation of the associated automatically-operated mechanisms which are operated by means of opposing sets of springs, in turn compressed by means of the gas pressure applied to pistons such that the accumulator mechanisms are not necessitated. All of the operating components thereby may be located to the rear of the weapon, and the resulting weapon is of relatively light weight and of excellent balance. It is thus rendered suitable for issuance to infantrymen as the basic shoulder-fired weapon, while affording the fire power inherent in a belt-fed fully automatic firearm.
In this design, as in any firearm, it would of course be desirable to reduce the deflections and stresses produced in the various operating parts so as to enable minimization of the size and mass of the various components to further enhance the handling advantages of the design.
While a dual piston operating rod assembly for a gas operated automatic firearm is disclosed in U.S. Pat. No. 3,999,461, this weapon design involves a forwardly located gas port requiring a significant mass of the weapon to lie forward of the receiver of the weapon, leading to the aforementioned disadvantages. In addition, each of the piston members performs different functions in the operation of the weapon such that true symmetry and balancing of forces is not achieved, albeit some reduction in the stress levels exerted on the components is achieved.
The manual actuation of the weapon disclosed in the above-cited patents to the present inventor is relatively cumbersome and it would likewise be advantageous to simplify the manipulations required in executing a manual actuation of the weapon.
The weapon disclosed in those patents also produces a relatively high pressure sliding movement by virtue of the design feature wherein the bolt is locked during firing by means of an oscillating bolt latch element, which is operated to release the bolt while the bolt was urged to retract under heavy pressure by a compressed spring in the opposing spring system. This arrangement obviously would produce a wear point in the mechanism, and it would be advantageous if such presssure could be relieved at least partially during the cycling of the bolt latch element.
Another capability which would be desirable in such weaponry is the automatic retention of the bolt in its fully retracted position during manual operation and also after the cessation of automatic fire, since this allows the ammunition belt to be removed from the breech, a fresh belt to be inserted, or to leave the breech clear to free a jammed cartridge, or to allow cooling of the chamber.
All of such improvements are described in the above-identified pending patent application Ser. No. 874,114, in which the bolt locking mechanism is unloaded during its operation, involving the use of a mass which is momentarily accelerated by compression springs in the interval of bolt unlocking. However, the mass is located in a relatively confined space and requires a material of very high density to provide the required mass for proper operation. This creates a critical design point in insuring the proper operation.
In addition, in the arrangement disclosed, the method of operating the feed trays utilized to advance the ammunition belt through the receiver relies on the use of spring forces exerted by a feed leaf spring.
While this approach is valid, the use of a more positive actuation would be desirable in such a critical part of the operating mechanism in which the relatively massive and non-precision formed belt links must be reliably advanced.
The feed trays themselves are of a relatively complicated configuration in the latter of the applications, due to the inward bias applied to these components throughout their stroking movement and could be advantageously simplified.
Accordingly, it is an object of the present invention to provide an arrangement for providing an inertia mass in the weapon design disclosed in the above-referenced pending patent application in which the bulk thereof may be considerably increased, allowing the component element to be formed from steel, while insuring reliable operation of the mechanism.
It is still another object of the present invention to provide a feed mechanism for this weapon design which actuates the movement of the feed trays in a more positive manner and in which the configuration of the feed trays is simplified.
It is still another object of the present invention to provide certain other design improvements to the gas operated automatic weapon described in the above-referenced pending patent application to certain of the feed mechanism components as will be described hereinafter.